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关键词： Amniotic membrane   Collagen   Umbilical cord   Fibrillogenesis   Triple Helicity  

摘要： The diverse application of collagen has created a need to discover renewable and economical sources with prevailing/improved physico-chemical properties. To address this scenario, the present study has extracted collagen from Human Amniotic Membrane (AM) and Umbilical cord, which are treated as medical waste and compared its physico-chemical properties. Collagen was extracted by pepsin solubilization using various salt concentrations (1 M, 2 M and 4 M). Umbilical Cord Collagen (UC) yield was 10% higher than Amniotic Membrane Collagen (AC). UC reported 58% higher sulphated glycosaminoglycan content than AC. Electrophoretic pattern of AC and UC in both disulphide bond reducing and non-reducing conditions showed bands corresponding to collagen type I, III, IV, V and XV. Collagen morphology was examined using SEM and the amino acid content was quantified by HPLC and LC-MS/MS. Triple helicity was confirmed by CD and FTIR spectra. Thermal transition temperature of AC and UC was found equivalent to animal collagen. Self-assembly, fibril morphology and spatial alignment was studied using AFM and DLS. Biocompatibility was analyzed using 3T3 fibroblast cells. In conclusion, UC with higher yield, presented with better physico-chemical, structural and biological properties than AC could serve as an efficient alternative to the existing animal collagen for diverse applications. (c) 2020 Elsevier B.V. All rights reserved.

关键词： Chitosan particles   Polysaccharides   Supramolecular chemistry   Thermodynamics   Self-assembly   Rational design  

摘要： Chitosan-based particles are widely proposed as biocompatible drug delivery systems with mucoadhesive and permeation enhancing properties. However, strategies on how to modulate the intended biological responses are still scarce. Considering that particle properties affect the biological outcome, the rational design of the synthesis variables should be proposed to engineer drug delivery systems with improved biological performance. The purpose of this review is to establish a deeper understanding of possible correlations between these variables and the particle properties from theoretical and experimental perspectives. The fundamental physicochemical knowledge of chitosan-based polyelectrolyte complexation and surface modification is discussed focusing on chitosan-TPP, polyelectrolyte complexes, and chitosan-surface modified PLGA or lipid particles. A set of design considerations is proposed to enable future investigation in the development of chitosan particles with modulated properties. The approach presented here contributes to the rational design of chitosan-based particles that meet different requirements for biological activities.

关键词： Yellow River   Xiaolangdi reservoir   Stable isotopes   Deuterium excess   Hydro-biogeochemical cycle  

摘要： Increasingly, modern hydrological technologies are dynamically altering river water flow and drastically affecting river hydrogeochemical cycle regimes globally. The present study focused on the reservoir discharges of artificial floodwaters that influence spatiotemporal variations in the physicochemical and stable isotope compositions in the lower Yellow River (LYR) of China. The surface water samples were collected at the nine sites along the LYR during the pre-, inter-and post-flood periods. Then, the collected samples were analysed with the following standard method. The delta D and delta O-18 slopes of the waterline clearly indicated that the prolonged reservoir water and different water flows impacted the hydrological cycle in the LYR regions compared to GMWL (global meteoric water line) and LMWL (local meteoric water line). The thermal stratification processes of the water in the largest reservoir slightly enriched the heavy isotopes, and physicochemical alteration was neglected. Statistical analysis of two-way ANOVA revealed that the p-values (p < 0.01, p < 0.05) were very strong for most of the variables between the periods, and the linear regression exhibited weak values (R-2 = 0.253, R-2 = 0.150) at the surface water temperature variations and suggested no significant influence of isotope composition. Overall, the Xiaolangdi reservoir water prolonged time rates, and artificial floodwater flow had a very small effect on the isotope composition;in particular, a large high turbidity concentration in the discharged artificial floodwaters was the only considerable ecological risk condition in the LYR. This kind of proper monitoring work is immensely important and prevents reservoirs from causing hydrological cycle impacts in the LYR and the adjacent coastal ecosystems.

关键词： Pleurotus nebrodensis   Polysaccharide   Molecular structure   NMR   In vitro fermentation   Short-chain fatty acid  

摘要： A high Mw(5012 kDa) polysaccharide (PNPS) from the fruiting body of Pleurotus nebrodensis was isolated using water extraction followed by ethanol precipitation. The structural characteristics and in vitro fermentation behaviors of this polysaccharide was investigated. Chemical composition analysis showed the total sugar content of PNPS was up to 97.20 +/- 1.80 wt%. Monosaccharide composition analysis showed PNPS contained mainly glucose (89.22 +/- 5.70mol%) while small percentage of mannose (5.60 +/- 0.74mol%) and galactose (5.18 +/- 0.33mol %) were also detected. According to the linkage pattern analysis (methylation analysis), PNPS comprised mainly 4-beta-D-Glcp (58.90 mol%), while other residues including alpha-D-Glcp, 6-alpha-D-Galp, 3,6-alpha-D-Manp, 3-beta-D-Glcp and 6-alpha-D-Glcp were detected with a comparable amount. Combined with results from 1D and 2D NMR spectrum, a proposed structure of PNPS was presented. In vitro fermentation of PNPS by gut microbiota showed total SCFA production of all treatment groups was higher than negative control group (NC) significantly (p < 0.05) after 48 h of fermentation. The formation of SCFAs was mainly acetic acid, followed by propionic acid and butyric acid, and the pH was decreased from 6.95 to 4.70. After 72 h, the total sugar content decreased from 5.813 +/- 0.87 mg/L to 0.23 +/- 0.065 mg/L, and the molecular weight of PNPS decreased. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Ti   Nb   Sn   Osteoblast   Oxide   Contact angle   Surface zeta potential  

摘要： Implanted tissue engineering devices interact with the host tissue through their surface in the first instance. Surface chemistry triggers cell activities that stimulate bone tissue-formation mechanisms for osteoblast maturation. In this work, the bioactivity of binary Ti-40Nb and Ti-10Sn and ternary Ti-10Nb-5Sn alloys, candidates for bioengineering applications, has been studied on their surface with a view to establish their osteogenic potential compared to that of c.p. Ti. Cellular population growth was used to assess proliferative and differentiative phenotypes (via protein and Alkaline Phosphatase markers), coupled with gene expression (i.e. Runx2 and OCN) to confirm maturation. The results show that Sn-containing alloys support cell bioactivity, increase metabolic activity (i.e. metabolites content) that indicate their preferred glycolytic pathway, promote cell attachment, differentiation and osteoblast maturation. Ti-40Nb, although also non-cytotoxic, retards osteoblastic differentiation and maturation. To elucidate the features that underpin this difference, their physical (i.e. wettability, electrical state near the surface) and chemical properties (i.e. oxide layer thickness and composition) were analysed independently from topology and roughness. It was concluded that composition (esp. TiO2 % content) is a more important factor than wettability and oxide layer thickness, and that although a negatively-charged surface (represented by the surface zeta potential) was preferential for cell bioactivity given its protein-adsorption readiness, its magnitude was not a defining cause.

关键词： Particulate organic carbon   Dissolved organic carbon   Fate modelling   POPs   PCB 209   Wastewaters  

摘要： The agricultural areas of a historically contaminated National Relevance Site (SIN Brescia Caffaro) in Italy are an ideal case for studying the long term vertical and horizontal movement of polychlorinated biphenyls (PCBs) in soil. Here, a former large producer of PCBs (Caffaro S.p.A.) discharged its wastewaters, contaminated by PCBs and other chemicals, to a ditch used for about 80 years as source of irrigation waters for the adjacent agricultural areas. This caused a spread of contamination along both a vertical and a horizontal soil gradient. PCB concentrations of about 80 congeners, including PCB 209, peculiar of Caffaro production, were measured in three areas, selected for their different soil properties and cultivation history. The contamination levels with depth ranged from about 30 mg/kg dry weight (d.w.) of soil in the top (plow) layer to less than 0.1 mg/kg d.w. at the depth of 1 m. The concentrations varied also horizontally, since each field was surface irrigated from the short edge of each field, showing that PCBs could spread with length halving the initial concentrations in the topsoil only after about 30-35 m. The concentration gradients detected were explained considering the historic soil use and its change with time, the pedological properties as well as PCB physico-chemical parameters and halflives, developing equations which could be employed as guidance tools for evaluating PCBs (and similar chemicals) movement and direct further studies. (c) 2020 Elsevier B.V. All rights reserved.

关键词： Metal nanoparticles   Gold   Nanoparticles   Plasmonics   Surface plasmon resonance  

摘要： Over the past few years, gold nanostars have gained significant relevance in biology and medicine, in particular, in imaging and photothermal therapy, also owing to their biocompatibility. Furthermore, they have improved the sensitivity of diagnostic assays and have been integrated in lab-on-chip platforms for low-cost, field-deployable devices. However, despite their widespread use, they have not found applicability beyond the research laboratories. One of the main reasons for this limitation has been the almost exclusive focus, until recently, on applications alone and not on the understanding of the fundamental properties of these particles, which has hampered reproducibility, stability, and overall reliability. Recently, however, a resurgence in the fundamental research of gold nanostars has dramatically improved our understanding of their synthesis, functionalization, properties, and thus their applicability. In this Perspective, the literature exploring and improving our knowledge of the physicochemical properties of gold nanostars is critically presented and framed within the specific context of biological and clinical applications. Furthermore, on the basis of the most recently reported results, a path forward is proposed, aimed at enabling an effective integration of these particles in the clinic.

关键词： chitin nanofibers   Pickering emulsion   essential oil   antibacterial activity  

摘要： Nowadays consumers are increasingly demanding food with fewer synthetic preservatives, which makes antimicrobial essential oils (EOs) from plants promising alternatives. In this work, surfactant-free emulsions were successfully fabricated from Cinnamon cassia oil (C. cassia oil) with partially deacetylated chitin nanofiber (ChNF) adopted as a Pickering stabilizer. The storage stability and microstructures of the emulsions with different concentrations of ChNF were studied in detail. As ChNF concentration increased, the emulsion droplet size decreased while the emulsion stability increased with stable periods as long as 90 days. This could be attributed to the Pickering stabilization realized by irreversible adsorption of the ChNF at the oil-water interface (revealed by fluorescent microscopy) and subsequent formation of an interdroplet ChNF network in the continuous phase, which was further strengthened in the presence of the aldehyde moiety in the C. cassia oil (verified by FTIR spectra). The rheological data and SEM images provided further evidence for network formation in the emulsions with increased ChNF concentration. Furthermore, the antimicrobial activity of the emulsion against Escherichia coli and the release patterns of EOs from emulsions were also investigated. The emulsions showed prolonged antibacterial activities but enhanced diffusion efficiency with the introduction of ChNF, which turned out to be a good encapsulation system for the controlled release of EOs. This work evidences the promising advantages of ChNF-stabilized Pickering emulsions as a facile EOs delivery system for application in food preservation and related fields.

关键词： Laboratory Instruction   Physical Chemistry   Inquiry-Based/Discovery Learning   Kinetics   Enzymes   Upper-Division Undergraduate  

摘要： In this guided inquiry experiment, students extract catecholase enzyme from apples to catalyze the oxidation of catechol. They follow the reaction using the UV-vis absorbance of the p-benzophenone produced to determine the Michaelis-Menten kinetic parameters. Students make selected experimental choices within a structured framework such as selecting the apple varietal, the pH of the reaction mixture, and the reaction inhibitor. The experiment has been tested at multiple universities in physical chemistry laboratory courses with both large and small enrollments. We describe the experiment and its implementation in both synchronously and asynchronously taught courses.

关键词： Chemical shift  

摘要： A series of electronic and physicochemical parameters were explored to determine their effect on experimental spectroscopic and photophysical data. Through a systematic obtention of a series of meso-(o-aryl)-BODIPYs, F-19 NMR spectra were analyzed and their fluorescence quantum yields in several solvents were measured. Experimental values of F-19 chemical shift difference Delta delta(F) correlate well with sigma-Hammett constants, which is indicative of the inductive nature of the functional groups on the fluorine atoms. A computational DFT exploration of rotational energy barriers, electrostatic potential maps, group electronegativity, charge partitions and hardness/softness provided insight into how those traits can be directly related to the measured features. Expanded understanding of such characteristics provides design arguments and a structure-property relationship, which in a more advantageous way, would help to understand the properties of the synthesized molecules and of future attempts that are structurally related.